linux-dev - Linux kernel development work

Age	Commit message (Collapse)	Author	Files	Lines
2018-07-04	net/sched: Make etf report drops on error_queue	Jesus Sanchez-Palencia	1	-2/+33
	Use the socket error queue for reporting dropped packets if the socket has enabled that feature through the SO_TXTIME API. Packets are dropped either on enqueue() if they aren't accepted by the qdisc or on dequeue() if the system misses their deadline. Those are reported as different errors so applications can react accordingly. Userspace can retrieve the errors through the socket error queue and the corresponding cmsg interfaces. A struct sock_extended_err* is used for returning the error data, and the packet's timestamp can be retrieved by adding both ee_data and ee_info fields as e.g.: ((__u64) serr->ee_data << 32) + serr->ee_info This feature is disabled by default and must be explicitly enabled by applications. Enabling it can bring some overhead for the Tx cycles of the application. Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-04	net/sched: Add HW offloading capability to ETF	Jesus Sanchez-Palencia	1	-1/+70
	Add infra so etf qdisc supports HW offload of time-based transmission. For hw offload, the time sorted list is still used, so packets are dequeued always in order of txtime. Example: $ tc qdisc replace dev enp2s0 parent root handle 100 mqprio num_tc 3 \ map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@1 2@2 hw 0 $ tc qdisc add dev enp2s0 parent 100:1 etf offload delta 100000 \ clockid CLOCK_REALTIME In this example, the Qdisc will use HW offload for the control of the transmission time through the network adapter. The hrtimer used for packets scheduling inside the qdisc will use the clockid CLOCK_REALTIME as reference and packets leave the Qdisc "delta" (100000) nanoseconds before their transmission time. Because this will be using HW offload and since dynamic clocks are not supported by the hrtimer, the system clock and the PHC clock must be synchronized for this mode to behave as expected. Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-04	net/sched: Introduce the ETF Qdisc	Vinicius Costa Gomes	1	-0/+384
	The ETF (Earliest TxTime First) qdisc uses the information added earlier in this series (the socket option SO_TXTIME and the new role of sk_buff->tstamp) to schedule packets transmission based on absolute time. For some workloads, just bandwidth enforcement is not enough, and precise control of the transmission of packets is necessary. Example: $ tc qdisc replace dev enp2s0 parent root handle 100 mqprio num_tc 3 \ map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@1 2@2 hw 0 $ tc qdisc add dev enp2s0 parent 100:1 etf delta 100000 \ clockid CLOCK_TAI In this example, the Qdisc will provide SW best-effort for the control of the transmission time to the network adapter, the time stamp in the socket will be in reference to the clockid CLOCK_TAI and packets will leave the qdisc "delta" (100000) nanoseconds before its transmission time. The ETF qdisc will buffer packets sorted by their txtime. It will drop packets on enqueue() if their skbuff clockid does not match the clock reference of the Qdisc. Moreover, on dequeue(), a packet will be dropped if it expires while being enqueued. The qdisc also supports the SO_TXTIME deadline mode. For this mode, it will dequeue a packet as soon as possible and change the skb timestamp to 'now' during etf_dequeue(). Note that both the qdisc's and the SO_TXTIME ABIs allow for a clockid to be configured, but it's been decided that usage of CLOCK_TAI should be enforced until we decide to allow for other clockids to be used. The rationale here is that PTP times are usually in the TAI scale, thus no other clocks should be necessary. For now, the qdisc will return EINVAL if any clocks other than CLOCK_TAI are used. Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>